Medical treatment of various illnesses or diseases commonly includes the use of one or more medical devices. Two types of medical devices that are commonly used to repair various types of body passageways are an expandable graft or stent, or a surgical graft. These devices have been implanted in various areas of the mammalian anatomy.
Old age, dietary habits and primary genetics can also lead to a common disease, atherosclerosis. Atherosclerotic plaques and blockages consist of lipids, fibroblasts and fibrin that proliferate and cause obstruction of a vessel. As the obstruction grows, the blood flow diminishes and reaches a level that is insufficient to meet the biological needs of one or more organs. The end result is defined as ischemia.
One purpose of a stent is to open a blocked or partially blocked body passageway. When a stent is used in a blood vessel, the stent is used to open the occluded vessel to achieve improved blood flow which is necessary to provide for the anatomical function of an organ. The procedure of opening a blocked or partially blocked body passageway commonly includes the use of one or more stents in combination with other medical devices such as, but not limited to, an introducer sheath, a guiding catheter, a guide wire, an angioplasty balloon, etc.
During the insertion of the stent, some disruption of the native body passageway can occur. This disruption to the body passageway can start a cascade of biological occurrences that can hinder the function of the implanted stent. When a stent is inserted into a blood vessel, a) platelets can be activated, b) smooth muscle cells can migrate and/or c) endothelial cells, which protect the vessel, can be disrupted thus leading to the cascade of clot formation. Clot formation can lead to the failure of the stent. The accumulation of platelets about the implanted stent is known as thrombosis.
Another medical procedure that is utilized frequently involves bypass (heart surgery), or peripheral (non-cardiac) grafting. This medical procedure entails using a surgical graft constructed of an artificial material that replaces or by-passes the diseased portion of the vessel. This procedure is accomplished by ligating the diseased portion of the vessel, temporarily stopping blood flow, and physically sewing in the surgical with a suture. The failure of the medical procedure commonly occurs at the suture (anastomoses) site. When the surgical graft is connected to a blood vessel, a) platelets can be activated, b) smooth muscle cells can migrate and/or c) endothelial cells, which protect the vessel, can be disrupted thus leading to the cascade of clot formation. The clot formation can lead to the failure of the surgical graft. The accumulation of platelets about the sutured regions is also known as thrombosis. During the insertion of the stent, some disruption of the native body passageway typically occurs. This disruption to the body passageway can start a cascade of biological occurrences that can hinder the function of the implanted stent. When a stent is inserted into a blood vessel, a) platelets can be activated, b) smooth muscle cells can migrate and/or c) endothelial cells, which protect the vessel. Such events can result in in-stent restenosis, vascular narrowing and/or restenosis. These failures can then lead to repeat procedures, amputation and/or other medical complications.
During and after a medical procedure, the patient is commonly placed on aggressive anti-platelet and/or anti-coagulation therapy. A major concern and side effect of such treatment is an increased incidence of bleeding complications. These bleeding complications can make the most routine procedure such as getting your teeth cleaned prohibited.
Many other types of diseases are treatable with stents, catheters, surgical grafts, and/or other devices inserted into vessels or other locations in the body. In addition, various types of orthopedic devices can be used to treat various diseased and/or damaged areas of a body. One desirable technique would be to deliver one or more biological agents directly to the site that has been treated and/or at the site of potential failure once a medical device has been inserted in the treatment site. In one non-limiting example, it would be desirable to have a medical device and/or a medical method or technique that can be used to deliver an anti-platelet and/or other medication to the region of a body passageway which has been treated by a stent or by another interventional technique. In another and/or alternative non-limiting example, it would be desirable to have a medical device that could deliver one or more biological agents over the short term (e.g, seconds, minutes, hours, days) with a potential controlled and/or uncontrolled burst effect of the one or more biological agents, and/or the long term (e.g., days, weeks, months, years) after the initial implantation of the medical device. In still another and/or alternative non-limiting example, it would be desirable to provide control over the delivery rate of one or more biological agents from the medical device, thus limiting or eliminating the systemic effects of taking a drug (e.g, orally, intravenously, etc.) over extended periods of time.
In view of the present state of medical device technology, there is a need and demand for a medical device that has improved procedural success rates and which inhibits or prevents the occurrence medical complications and/or failure rates of the implanted medical device. There is also a need and demand for a medical device in the form of a stent or surgical graft that has improved procedural success rates and which inhibits or prevents in-stent restenosis, vascular-narrowing and/or restenosis long after the stent or surgical graft has been inserted into the body passageway.